Crushing: Two-stage closed-circuit crushing and screening process was adopted, and the size of crushing product was ≤12mm.
Grinding & classification: One-stage closed-circuit grinding and classification process was adopted. Ball mill - classifier unit + cyclone were used in the grinding & classification, and the classification fineness was -200 mesh (60%).
Cyanide leaching: The cyanide leaching adopted the double impeller agitation leaching tank with eight-stage of leaching, 45% of leaching concentration and 48 hours of leaching time. Besides, the high-pressure Roots fan was used for air supply in the leaching process. Dehydration, washing of filter cake: After the leaching, the tailings were dehydrated to get the gold, silver and copper-containing pregnant solution liquid, and the filter cake was fully washed to get the gold-containing liquid. After the dehydration, the filter cake was sent to the tailings yard for stockpiling, and recovering the copper through the copper acid leaching later.
Recovery of cuprous sulfide: The gold, silver and copper-containing precious liquid was reacted with sodium bisulfide and concentrated sulfuric acid, which produced the cuprous sulfide. After the precipitation, the cuprous sulfide was neutralized by adding the alkali, and the neutralized solution was dehydrated by the press filter, the filter cake was cuprous sulfide, and the filtrate was used to recover the gypsum. Recovery of gypsum: The filtrate discharged was transported to the neutralization tank by the anticorrosive pump, and the neutralized solution was transported to the gypsum precipitation thickener for precipitation. The thickener underflow was transported to the medium pressure press filter for obtaining the gypsum, and the gold-containing filtrate was sent to the gold recovery operation. Recovery of hydrogen cyanide gas: the hydrogen cyanide gas was generated during the recovery process of cuprous sulfide. the generated hydrogen cyanide gas was uniformly collected into the absorption tower, and reacted with NaOH through spraying, then produced the NaCN solution. The NaCN solution was returned to the cyanide leaching system for recycling. Carbon adsorption of gold-containing pregnant solution: The gold-containing pregnant liquid entered to the carbon adsorption tank for gold adsorption, adsorbing the gold from the liquid phase to the activated carbon, and the lean liquid returned to the production process for recycling. Desorption electrolysis and smelting: the adsorbed and saturated gold loaded carbon was transported to the desorption electrolysis system to obtain the gold mud, then gold mud was sent to the smelting room to obtain the alloy gold.